a. A customer unexpectedly paid a balance of $3,600, which had been written off in a prior year.

b. A customer balance of $1,400 from a prior year was determined to be uncollectible and was written off.

c. On December 31, the Allowance for Doubtful Accounts account has a normal balance of $3,500 before any year-end adjustment forbad debts. However, the company estimated that it still needs to record $700 more of bad debts for the year.